Power sander

ABSTRACT

A HOUSING MEMBER, WHICH SERVES AS A HANDLE FOR THE POWER SANDER, INCLUDES A DOWNWARDLY OPENING CAVITY HAVING A SUBSTANTIALLY CONTINUOUS TAPERED WALL SURFACE. A PNEUMATIC MOTOR IS RECEIVED WITHIN THIS CAVITY, THE MOTOR HOUSING OR FRAME DEFINING A SUBSTANTIALLY CONTINUOUS SURFACE IN SPACED, CONFRONTING AND COEXTENSIVE RELATION WITH THE TAPERED SURFACE. A RESILIENT SLEEVE OR BOOT HAS A FLANGE AT THE UPPER END THEREOF RECEIVED BETWEEN THESE SURFACES AND SECURELY WEDGED THEREBETWEEN BY FASTENING MEANS WHICH ENGAGE THE HOUSING MEMBER AND THE MOTOR HOUSING FOR DRAWING THE LATTER UP INTO THE CAVITY. THE LOWER END OF THIS RESILIENT SLEEVE IS CLAMPED TO THE RIGID BACKING PLATE OF THE SANDING PAD ASSEMBLY BY A PAIR OF RING MEMBERS, ONE OF THESE RING MEMBERS BEING SECURED TO THE RIGID BACKING PLATE. THE DRIVE SHAFT OF THE MOTOR MOUNTS ECCENTRIC MEANS WHICH ARE CONNECTED TO THE BACKING PLATE FOR IMPARTING ORBITAL VIBRATORY MOTION TO THE SANDING PAD ASSEMBLY UPON OPERATION OF THE MOTOR. OPPOSITE ENDS OF A SHEET OF SANDPAPER ARE SECURED TO THE SANDING PAD ASSEMBLY BY SPRING-BIASED CLAMPS, THESE CLAMPS BEING CONFIGURED AND ARRANGED SUCH THAT A PULLING FORCE ON THE SANDPAPER TENDS TO INCREASE THE CLAMPING FORCES.

Jan 19, 1971- V w, G 35553743 POWER SANDER Filed April 15, less INVENTOR. W'LLIAM L. GEIGER ATTORNEYS.

United States Patent O 3,555,743 POWER SANDER William L. Geiger, Chicago, Ill., assignor to Skil Corporation, Chicago, 11]., a corporation of Delaware Filed Apr. 15, 1968, Ser. No. 721,406 Int. Cl. B24b 23/00 US. Cl. 51-170 3 Claims ABSTRACT OF THE DISCLOSURE A housing member, which serves as a handle for the power sander, includes a downwardly opening cavity having a substantially continuous tapered wall surface. A pneumatic motor is received within this cavity, the motor housing or frame defining a substantially continuous surface in spaced, confronting and coextensive relation with the tapered surface. A resilient sleeve or boot has a flange at the upper end thereof received between these surfaces and securely wedged therebetween by fastening means which engage the housing member and the motor housing for drawing the latter up into the cavity. The lower end of this resilient sleeve is clamped to the rigid backing plate of the sanding pad assembly by a pair of ring members, one of these ring members being secured to the rigid backing plate. The drive shaft of the motor mounts eccentric means which are connected to the backing plate for imparting orbital vibratory motion to the sanding pad assembly upon operation of the motor. Opposite ends of a sheet of sandpaper are secured to the sanding pad assembly by spring-biased clamps, these clamps being configured and arranged such that a pulling force on the sandpaper tends to increase the clamping forces.

OBJECTS OF THE INVENTION A primary object of the present invention is the provision of a power sander having new and improved means connecting the housing of the sander to the sanding pad assembly thereof.

Another object of the invention is the provision of a power sander of the type described, wherein a flexible sleeve or boot has opposite ends thereof connected respectively to the sander housing and the sanding pad assembly, opposite ends of this sleeve being connected to these parts solely by radial squeezing forces.

Still another object of the present invention is the provision of a power sander including a housing member having a cavity, a motor received within such cavity, fastening means for drawing the motor into the cavity and at the same time establishing a wedging grip with the upper end of a flexible sleeve, the lower end of which sleeve is connected to the sanding pad assembly.

Another object of the present invention is the provision of new and improved clamp means for securing a sheet of sandpaper to the sanding pad assembly of a power sander.

These and other objects and advantages of the invention will become apparent from the following specification disclosing a preferred embodiment shown in the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical central section taken longitudinally through a sander constructed in accordance with the Present invention; and i 3,555,743 Patented Jan. 19, 1971 FIG. 2 is a fragmentary view taken along the line 22 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT The sander includes a housing member 10, preferably of plastic construction, which is shaped to serve as the handle of the power sander. This member has a downwardly opening cavity 11, such cavity including a substantially continuous side wall 12 which tapers downwardly and outwardly. A pneumatic motor is arranged within the cavity 11 and includes upper and lower frame plates 14 and 15, respectively, and one or more wall members 16. The frame plates 14 and 15 are apertured for rotatably receiving a shaft 18, opposite ends of the latter being received in ball-bearing assemblies 19 and 20, which ball-bearing assemblies are mounted in recesses 21 and 22, respectively. The housing member 10 is provided with a cavity 24 for receiving the ball-bearing assem bly 19, such cavity being in communication with the cavity 11.

The pneumatic motor, which is preferably of the type disclosed and claimed in Johansson application, Ser. No. 644,163, filed July 7, 1967, now abandoned, includes a plurality of vanes 25 secured to the shaft 18 for imparting rotation thereto. Fluid under pressure is admitted to these vanes through passageway means (not shown), such passageway means communicating with a bore 26 formed in a member 28 which constitutes a portion of the motor. The bore 26 opens into an enlarged bore 29 which is plugged at the lower end thereof by a plug 30. This plug includes an annular recess mounting an O-ring 31 for establishing a sealing engagement with the bore 29. The plug 30 includes a blind bore 32 receiving one end of a spring 33, the other end of this spring engaging a ball 34 adapted for sealing engagement with a valve seat surface 36 provided at the juncture of the bores 26 and 29.

A valve-operating rod 38 is mounted for reciprocal sliding movement in a bore formed in the housing member 10. The rod engages a valve-operating stem 39 which is mounted for reciprocal sliding movement in bores formed in the motor frame 14 and the motor part 28. The lower end of this valve-operating stem extends into the bore 26 for engagement with the ball 34. It will be apparent that downward movement of the rod 38 will serve to unseat the ball 34 thereby to establish communication between the bore 26 and the bore 29.

An operating lever 40 is provided for depressing the rod 38. The lever 40 is in the form of a spring plate having an aperture 41 which receives a fitting 42, the latter being threadingly engaged with a threaded bore 43 formed in the motor part 28. It will be apparent the spring 33 will serve to seat the ball 34 against the valve seat 36 and at the same time raise the operating stem 39 and the rod 38.

The fitting 42 includes a threaded bore 45 for threading engagement with one end of an air hose (not shown). The bore 45 communicates with a reduced-in-diameter bore 46, the latter opening into the bore 43. A passageway 48 communicates the bore 29 with the bore 43. It will be apparent that when the operating lever 40 is depressed, air under pressure admitted at the bore 45 will be allowed to pass into the motor for operating the same.

At this time, it should be mentioned the housing member 10 is provided with an appropriate opening adjacent one side thereof to accommodate the fitting 42 and the motor part 28. As will become apparent herein, the various motor parts are secured together by the same fastening means used to secure the motor in the cavity 11 of the housing member The lower end of the shaft 18 supports a member 50 which is essentially a crankshaft, the latter supporting a subshaft 51 in eccentric relation with the shaft 18. The subshaft 51 is rotatably received within a ball-bearing assembly 52. This ball-bearing assembly is in turn received within the central, cup portion 54 of a ring member 55 which is secured to the rigid backing plate 56 of the sanding pad assembly. The ball-bearing assembly 52 is captured or held within the cup portion 54 by a plate 57 threadingly engaged with threads formed in the cup portion 54 at the lower end thereof. The plate 57 is provided with a plurality of blind bores 58 for receiving an appropriate tool to impart rotation of the plate '57 relative to the cup portion 54.

The backing plate 56, which is of rectangular planar construction, has suitably secured thereto a yieldable backing pad 60. The pad 60 is connected to the rigid backing plate 56 by four fasteners, one fastener being illustrated and designated 61.

A flexible sleeve or boot 62, preferably formed of rubber, serves as a means for establishing a connection between the housing member 10 and the sanding pad assembly. The sleeve 62, which is circular-in-cross-section, has at the upper end thereof a continuous flange portion 60a which engages the tapered surface 12 and which is received within an annular, continuous recess 63 formed in the motor wall 16. A plurality of fasteners 64 extend upwardly through suitable bores in the motor frame parts 14 and and in the motor wall 16. The upper ends of these fasteners are threaded and threadingly engage bushings or metal inserts 65 secured within blind bores in the housing 10. These fasteners 64 serve to secure the various motor parts together and also to draw the motor up into the cavity 11. Because of the tapered surface 12, it will be appreciated that as the motor is drawn upwardly into the cavity 111, the flange portion 60a will be securely wedged between the tapered surface 12 and the annular recess 63 thereby serving as a simple but effective means for establishing a tight connection at the upper end of the sleeve 62.

The lower end of the sleeve 62 includes a flange portion 60b which engages a ring surface 68 defined by the member 55. A C-clamp member 69 having fastening means 69a at its ends, engages the outer surface of the flange portion 60b for squeezing the latter against the ring surface 68. This means for establishing a connection at the lower end of the sleeve 62 obviates the use of fastening means which extend through the backing plate 56 as found in prior art structures.

Unique clamping means are provided for securing a sheet of sandpaper to the sanding pad assembly. It will be understood that identical clamping means are provided at each end of the sanding pad assembly-only one of such clamps will be described in detail herein.

A movable clamp member 70 has ears 70a receiving opposite ends of a pin 71, the latter being supported by appropriate bracket means (not shown) secured to the backing plate 56. The movable clamp member 70 has an inner surface portion defining a clamp surface 700 in confronting coextensive relation with a portion of an upstanding flange 56a of the backing plate 56, such portion defining a flxed clamp surface. It will be understood the flange 56a and the clamp surface 700 extend continuously across or transversely of the sander as indicated in FIG. 2. A spring member 74 is coiled one or more times around the pin 71; this spring member has opposite ends thereof abutting the plate 56 and the underside of the member 70 for swinging the latter such that the clamp surface 70c is urged toward the flange 56a.

The operators hand engages the portion 70b of the clamp 70 rocking the latter to separate the clamp surface 70 from the flange 56a thereby to allow entry of one end of a sheet of sandpaper 76. It will be apparent the spring 74 will act to squeeze this end of the sandpaper between the flange 56a and clamp surface 700. It will also be apparent that the flange 56a and the surface 700, which define the clamping surfaces for the sandpaper, are arranged relative to the pivot axis 71 such that a pulling force on the sandpaper 76 will tend to increase the pressure between the flange 56a and the surface 700.

It should be apparent that according to the present invention, a new and improved power sander has been provided. The flexible sleeve or boot prevents unwanted displacement of the sanding pad assembly relative to the housing portion but flexes to accommodate the orbital vibratory movement of the sanding pad assembly. Opposite ends of the sleeve are secured to both the housing and the backing pad assembly only by radial squeezing forces obviating numerous separate fastening means employed in prior art structures. The sleeve 62' establishes a built-in seal between the housing of the tool and the sanding pad assembly. The unique clamps for securing a sheet of sandpaper to the sanding pad assembly may be quickly and easily operated and are arranged such that a pulling force on the sandpaper tends to increase the clamping or squeezing action at opposite ends of the sheet of sandpaper. The clamps for opposite ends of the sandpaper have a low profile minimizing the possibility of their being engaged by the operators clothing and also contributing to the aesthetics of the power sander.

While the invention has been shown in but one form, it will be obvious to those skilled in the art it is not to be so limited. On the contrary, the invention is susceptible of various forms and modifications without departing from the spirit and scope of the appended claims.

I claim:

1. In an orbital sander, the improvement comprising, a housing member having a cavity opening at the bottom thereof, such cavity including a substantially continuous side wall with a downwardly and outwardly extending tapered surface, a motor arranged within said cavity, which motor includes a housing part having a substantially continuous formation in spaced, confronting, coextensive relation with said tapered surface, said motor having a vertically disposed drive shaft and eccentric means on the lower end thereof, a resilient sleeve in generally coaxial relation with said shaft, which sleeve has a continuous portion at the upper end thereof received between said surface and said formation, fastening means engaged with said housing member and said housing part for drawing the latter upwardly into said cavity and thereby securely wedging said sleeve portion between said surface and said formation, a generally planar sanding pad assembly having a rigid backing plate, said eccentric means being connected to said backing plate for imparting an orbital vibratory motion to said pad assembly upon operation of said motor, other fastening means connecting the lower end of said sleeve to said backing plate, said sleeve and said eccentric means constituting the only means supporting said pad assembly.

2. The improvement according to claim 1 wherein said other fastening means comprise, a fixed ring secured to said backing plate and in coextensive engagement with the inside of said sleeve at the lower end thereof, a clamping ring engaging the outside of said sleeve at the lower end thereof for squeezing the sleeve adjacent said fixed ring.

3. In an orbital sander of the type including a housing enclosing a motor, eccentric means driven by said motor, and a sanding pad assembly connected to said eccentric means for being subjected to orbital vibratory motion upon operation of said motor, the improvement comprising, a resilient sleeve having opposite ends thereof connected respectively to said housing and said pad assembly by separate first and second clamping means only, each of said clamping means serving to engage said sleeve solely by radial squeezing thereof, said sleeve and said eccentric means serving as the only means establishing connections between said housing and said pad assembly, said first clamping means being defined by said housing having a cavity including a substantially continuous outer wall in confronting, spaced relation with said inner Wall, said inner and outer Walls snugly engaging respective inner and outer surfaces of said sleeve, and fastening means connecting said frame to said housing.

References Cited UNITED STATES PATENTS WILLIAM R. ARMSTRONG, Primary Examiner US. Cl. X.R. 

